This invention relates generally to medical or surgical instruments, and is more particularly directed to a two-piece disposable vaginal speculum.
Many disposable, plastic vaginal specula of this general type have been previously proposed, typically employing a Graves or Peterson blade. These are often formed of a moldable synthetic resin such as polystyrene or polypropylene and can be clear or colored. These disposable vaginal specula are particularly useful for high-volume clinical users, such as clinics which specialize in the detection of venereal disease or cancer of the cervix. Because the practitioner or clinician should have both hands free during an examination, the vaginal speculum is preferably lockable at any of several open positions, and then easily released for removal. The speculum should have at least five open positions. Generally, certain lubricants for the speculum are not favored, because they can spoil a pap smear application, so a plastic material is generally employed for which water or silicone solution provides a satisfactory lubricant.
It is desirable that the design of the speculum be simple to reduce molding and tooling costs. In particular, these specula should be constructed with a minimum number of parts, ideally, only an upper and lower part.
However, there has been a problem in constructing such a speculum which will reliably remain in an open, locked position. This arises when the pressure exerted on the blade by the vaginal wall distorts the locking parts of the speculum, which, in order to be low-cost and disposable, is constructed of plastics material that is distorted by pressure.
Another problem of prior-art vaginal specula is that they often produce noisy clicks when being opened within the patient. This noise is caused by the ratchet action of the speculum. Although the ratchet action itself is not harmful, the clicking noise is always disturbing to the patient, and sometimes causes a traumatic reaction, making examination more difficult.
Typical vaginal specula are disclosed, for example, in U.S. Pat. Nos. 3,568,665 of Mar. 9, 1971 and 3,752,149 of Apr. 18, 1973. A three-part disposable speculum is shown in U.S. Pat. No. 3,716,047 of Feb. 13, 1973, and several two-part disposable specula are shown in U.S. Pat. Nos. 3,246,646 of Apr. 19, 1966; 3,332,414 of July 25, 1967; 3,650,266 of Mar. 21, 1972; 3,985,125 of Oct. 12, 1976; and 3,890,961 of June 24, 1975.